The present invention relates to a cooling structure that releases heat from a brushless motor.
Japanese Laid-Open Patent Publication No. 2008-54391 proposes a cooling structure that releases heat from a brushless motor.
The brushless motor described in Japanese Laid-Open Patent Publication No. 2008-54391 includes a stator, a rotor rotated in the stator, and a motor shaft arranged integrally with the rotor. A cooling fan is coupled to the motor shaft to draw ambient air into the stator. This dissipates the heat generated by the brushless motor.
The stator includes a stator core, an insulator, and a coil. The stator core includes a cylindrical portion and teeth extending from an inner circumferential surface of the cylindrical portion. The insulator covers the inner circumferential surface of the cylindrical portion, first and second end surfaces that are adjacent to the inner circumferential surface, and the teeth. The coil is wound around the teeth that are covered by the insulator.
The brushless motor includes exposed portions that expose the inner circumferential surface of the cylindrical portion from the insulator between adjacent ones of the teeth in the circumferential direction. This increases the heat radiation efficiency of the cooling fan.
However, the exposed portions, which are not covered by the insulator, in the inner circumferential surface of the cylindrical portion in the stator core may adversely affect the insulation performance.